mouse and keyboard crash comp after sp3 update

Hello all, im have a strange problem, i did a sp3 update on my xp media center windows, and it wouldnt boot at all, so after alot of trial and error i found that windows boots fine if my mouse and keyboard arent plugged in, but the second i plug them in after windows starts my comp crashes with this error system32drivers\mup.sys error....so i cant use my mouse or keyboard at all, i would love to just remove the stupid SP3 update. can any1 help me plzzz im lost, i looked in bios all usb legacy is on,and i turned off auto reboot, just seems strange windows boots fine with out those devises in but crases soon as i plug them in , so i cant do anything on my comp.any help is welcomed, and feel free to email me at <email address removed by Administrator to prevent harvesting by spammers> with any helpful ideas, as i can only get online at work now.ty all and God bless :cry